ira.c (struct equivalence): Change member "is_arg_equivalence" and "replace" into boolean bitfields...

gcc/
        * ira.c (struct equivalence): Change member "is_arg_equivalence" and
        "replace" into boolean bitfields; turn member "loop_depth" into a short
        integer; add new member "no_equiv" and "reserved".
        (no_equiv): Set no_equiv of struct equivalence if register is marked
        as having no known equivalence.
        (update_equiv_regs): Check all definitions for a multiple-set
        register to make sure that the RHS have the same value.

Co-Authored-By: Jeff Law <law@redhat.com>

From-SVN: r216169